THE EVALUATION OF MICROPLASTIC PARTICLES IN THE WATER AREA OF LAKE LADOGA

Abstract

In this article, we present the results of studying the content of microplastics in the surface layer of water column and sediments in the water area of Lake Ladoga. The sampling, preparing and analysis were carried out in 2018-2021. We used NOAA methods adapted for freshwater bodies to prepare sediment samples and extract microplastics from sediments. An optical microscope was used to identify shape, size and colour of microplastic particles. The chemical analysis of studied particles was carried out using methods of Raman spectrometry. The results showed that microplastic particles are present in all samples. The highest concentrations of microplastics were fixed near urban districts (Priozersk and Sortavala) and industrial areas (the plant in the city of Pitkyaranta). The increased concentrations were also observed in the areas of river inflows (the Vuoksi, the Jänisjoki and the Volkhov rivers). Regarding the shape, fibers prevailed to a large extent (97%). The largest number of particles by size were found within the range of 60-1000 µm (60%), the number of particles decreased with increasing of their size. The statistically significant correlation between the particle-size composition of sediments and concentrations of microplastic particles in these sediments was not found. The spectral analysis of chemical composition of particles showed that the most common types of microplastics in the water area of the Ladoga were polyamide and polyethylene; polyethylene terephthalate and polycarbonate particles were also found. Apart from the plastic particles, a large number of cotton fibers were fixed.